"We've sampled a number of animals before the bounty in 1888 till 1909 and sequenced the DNA of a small piece of the genome," says Menzies.

"Individuals show about five base diffferences between dogs, which is equivalent to 2 per cent of DNA. In the Tasmanian tiger it looks like only half a per cent of that region is variable, much less than what we would expect in a healthy population."

Menzies says there could be a number of reasons for this.

"It could have been caused by previous bounties in Tasmania lowering the number of individuals," he says. "More likely it's part of a longer history of becoming less genetically diverse in Tasmania."

The specimens used in the study were collected by museums as far afield as Berlin and Cambridge, some almost 160 years old.

Isolating DNA in such fragile specimens is a challenge, with samples taken carefully from bones and pelts.

Geographic isolation

Menzies says it's an important study, because genetic diversity is crucial to the long term survival of a species.

"We have to look at genetic diversity as something that we need to manage within the Australian landscape and we need to keep it intact as much as possible," he says.

Lack of genetic diversity is a problem facing a number of Tasmanian species, due in part to the island state's geographic isolation.

Menzies says this includes the Tasmanian devil, which is currently threatened by facial tumour disease.

"We need to look at all of Tasmania's fauna as a group ... and look at what we can do to better manage those populations so that they can deal with stress in the environment."